Byzantine Consensus in Low-Power Edge Meshes
Distributed systems research mostly assumes cloud conditions: low latency, reliable networking, ample compute. The edge is a different world — intermittent connectivity, heterogeneous hardware, strict power budgets.
When we built Edge Lattice, we needed a consensus protocol that could handle Byzantine faults (malicious or corrupted nodes, not just crashes) on a mesh where individual nodes might be solar-powered with 30-minute duty cycles.
What PBFT Assumes (and What We Don't Have)
Practical Byzantine Fault Tolerance (Castro & Liskov, 1999) requires:
None of these hold in our deployment environments.
Our Modifications
1. Sparse quorum selection: Instead of broadcasting to all n nodes, we use a gossip-based approach to select a rotating quorum of √n nodes per round. Message complexity drops from O(n²) to O(n·√n).
2. Probabilistic view-change: Rather than timeout-based view-change (which misfires on slow links), we use a gossip-estimated liveness score per leader node.
3. Commitment DAG: We replace the linear commit chain with a DAG structure that tolerates out-of-order arrival without protocol violations.
Results on a 40-Node Testbed
| Protocol | Consensus latency | Max Byzantine nodes | Power/node |
|---|---|---|---|
| Vanilla PBFT | 180ms | n/3 | — |
| Ours | 2.1ms | n/3 | 0.8W |
Note: our latency advantage comes primarily from the quorum reduction — we're comparing different protocol shapes, not claiming a direct algorithmic speedup over PBFT.